The Lib Dems will neither back nor oppose the Tory bill to guarantee an in/out referendum on EU membership. Photograph: Stefan Rousseau/PA

Nick Clegg has defeated an attempt by senior Liberal Democrats to match the Tories by guaranteeing to hold a "seductive" referendum on Britain's EU membership in the next parliament. The deputy prime minister, who has faced direct calls from ministers for a change of stance on the EU, won the agreement of the Lib Dem parliamentary party to stand by the current policy. This is to hold a referendum only if UK sovereignty is passed to the EU. The Tories would go further by guaranteeing an in/out referendum on Britain's EU membership in 2017 regardless of the result of negotiations on the future of the EU.

Clegg defeated an attempt by senior party figures to guarantee a referendum in the party's general election manifesto. Tim Farron, the party president, and Simon Hughes, the former Lib Dem deputy leader and justice minister, have spoken in favour of a referendum. Calls for a referendum increased after the Lib Dems saw the party's crop of elected MEPs crash from ten to one in last month's European parliamentary elections.

The deputy prime minister won the party's agreement to maintain the same position on the EU in the autumn when the Tories reintroduce a private member's bill to guarantee an in/out referendum on Britain's EU membership by the end of 2017. The Lib Dems will neither support nor oppose the bill, which is being tabled by the Tory MP Bob Neill, to avoid being seen to "bang on about Europe".

But the Lib Dems will introduce a new set of policies on immigration over the coming weeks for their general election manifesto. One source said the new immigration policies will show that the party is listening to the concerns of the electorate.

A senior Lib Dem said of the party's position on the EU: "Our views are clear. When the rules of the European Union change there will be a referendum as we have enshrined in law. Some people may think it would be seductive to change our position on Europe but we are not going to spend the next ten months banging on about the referendum bill. We will leave that to others.

"We have listened to the electorate at the last election and will be setting out clearly our views on immigration and its impact upon society which is at the core of this issue. That is what people really care about."

Critics of the leadership believe that failing to guarantee a referendum may leave the party badly exposed to a Tory assault at the election. One source said: "We will just end up looking shifty if we refuse to guarantee a referendum. We will give way anyway if we enter into a new coalition with the Tories. So why don't we just turn round and offer a referendum now?"

Farron recently told the Times that the Lib Dems should guarantee a referendum but not on the prime minister's timetable. Farron said: "I think the British people should be given a say on whether we should be in or out of the EU but [the prime minister's] policy is like playing poker with all your cards showing."